// Copyright 2008 the V8 project authors. All rights reserved.
// Copyright 1996 John Maloney and Mario Wolczko.

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA


// This implementation of the DeltaBlue benchmark is derived 
// from the Smalltalk implementation by John Maloney and Mario 
// Wolczko. Some parts have been translated directly, whereas 
// others have been modified more aggresively to make it feel 
// more like a JavaScript program.
package deltablue {


/**
 * A JavaScript implementation of the DeltaBlue constrain-solving
 * algorithm, as described in:
 *
 * "The DeltaBlue Algorithm: An Incremental Constraint Hierarchy Solver"
 *   Bjorn N. Freeman-Benson and John Maloney
 *   January 1990 Communications of the ACM,
 *   also available as University of Washington TR 89-08-06.
 *
 * Beware: this benchmark is written in a grotesque style where
 * the constraint model is built by side-effects from constructors.
 * I've kept it this way to avoid deviating too much from the original
 * implementation.
 */


/* --- O b j e c t   M o d e l --- */

/*
Object.prototype.inherits = function (shuper) {
  function Inheriter() { }
  Inheriter.prototype = shuper.prototype;
  this.prototype = new Inheriter();
  this.superConstructor = shuper;
}
*/

public class OrderedCollection {
    private var elms;
    
    public function OrderedCollection() {
      this.elms = new Array();
    }
    
    public function add(elm) {
      this.elms.push(elm);
    }
    
    public function at(index) {
      return this.elms[index];
    }
    
    public function size() {
      return this.elms.length;
    }
    
    public function removeFirst(){
      return this.elms.pop();
    }
    
    public function remove(elm) {
      var index = 0, skipped = 0;
      for (var i = 0; i < this.elms.length; i++) {
        var value = this.elms[i];
        if (value != elm) {
          this.elms[index] = value;
          index++;
        } else {
          skipped++;
        }
      }
      for (var i = 0; i < skipped; i++)
        this.elms.pop();
    }
} // class OrderedCollection


/* --- *
 * S t r e n g t h
 * --- */
public class Strength {
    /**
     * Strengths are used to measure the relative importance of constraints.
     * New strengths may be inserted in the strength hierarchy without
     * disrupting current constraints.  Strengths cannot be created outside
     * this class, so pointer comparison can be used for value comparison.
     */
    public var strengthValue;
    public var name;

    // Strength constants.
    static public const REQUIRED:Strength        = new Strength(0, "required");
    static public const STONG_PREFERRED:Strength = new Strength(1, "strongPreferred");
    static public const PREFERRED:Strength       = new Strength(2, "preferred");
    static public const STRONG_DEFAULT:Strength  = new Strength(3, "strongDefault");
    static public const NORMAL:Strength          = new Strength(4, "normal");
    static public const WEAK_DEFAULT:Strength    = new Strength(5, "weakDefault");
    static public const WEAKEST:Strength         = new Strength(6, "weakest");
    
    public function Strength(strengthValue, name) {
      this.strengthValue = strengthValue;
      this.name = name;
    }
    
    static public function stronger(s1, s2) {
      return s1.strengthValue < s2.strengthValue;
    }
    
    static public function weaker(s1, s2) {
      return s1.strengthValue > s2.strengthValue;
    }
    
    static public function weakestOf(s1, s2) {
      return weaker(s1, s2) ? s1 : s2;
    }
    
    static public function strongest(s1, s2) {
      return stronger(s1, s2) ? s1 : s2;
    }
    
    public function nextWeaker() {
      switch (this.strengthValue) {
        case 0: return Strength.WEAKEST;
        case 1: return Strength.WEAK_DEFAULT;
        case 2: return Strength.NORMAL;
        case 3: return Strength.STRONG_DEFAULT;
        case 4: return Strength.PREFERRED;
        case 5: return Strength.REQUIRED;
      }
     // return a dummy val here to please compiler
     return Strength.WEAKEST;
    }
    
} // class Strength


/* --- *
 * C o n s t r a i n t
 * --- */
public class Constraint {
    /**
     * An abstract class representing a system-maintainable relationship
     * (or "constraint") between a set of variables. A constraint supplies
     * a strength instance variable; concrete subclasses provide a means
     * of storing the constrained variables and other information required
     * to represent a constraint.
     */
    public var strength;
    
    public function Constraint(strength) {
      this.strength = strength;
    }
    
    /**
     * Activate this constraint and attempt to satisfy it.
     */
    public function addConstraint() {
      this.addToGraph();
      planner.incrementalAdd(this);
    }
    
    
    // functions to be overridden by children
    public function addToGraph() {}
    public function output() {}
    public function chooseMethod(mark) {}
    public function isSatisfied() {return false;}
    public function markInputs(mark) {}
    public function removeFromGraph() {}
    public function markUnsatisfied() {}
    public function inputsKnown(mark=null) {return false;}
    public function recalculate() {}
    public function execute() {}
    
    /**
     * Attempt to find a way to enforce this constraint. If successful,
     * record the solution, perhaps modifying the current dataflow
     * graph. Answer the constraint that this constraint overrides, if
     * there is one, or nil, if there isn't.
     * Assume: I am not already satisfied.
     */
    public function satisfy(mark) {
      this.chooseMethod(mark);
      if (!this.isSatisfied()) {
        if (this.strength == Strength.REQUIRED)
          print("Could not satisfy a required constraint!");
        return null;
      }
      this.markInputs(mark);
      var out = this.output();
      var overridden = out.determinedBy;
      if (overridden != null) overridden.markUnsatisfied();
      out.determinedBy = this;
      if (!planner.addPropagate(this, mark))
        print("Cycle encountered");
      out.mark = mark;
      return overridden;
    }
    
    public function destroyConstraint() {
      if (this.isSatisfied()) planner.incrementalRemove(this);
      else this.removeFromGraph();
    }
    
    /**
     * Normal constraints are not input constraints.  An input constraint
     * is one that depends on external state, such as the mouse, the
     * keybord, a clock, or some arbitraty piece of imperative code.
     */
    public function isInput() {
      return false;
    }

} // class Constraint

/* --- *
 * U n a r y   C o n s t r a i n t
 * --- */
public class UnaryConstraint extends Constraint {
    /**
     * Abstract superclass for constraints having a single possible output
     * variable.
     */
    protected var myOutput;
    protected var satisfied;
     
    public function UnaryConstraint(v, strength) {
      super(strength);
      this.myOutput = v;
      this.satisfied = false;
      this.addConstraint();
    }
    
    //UnaryConstraint.inherits(Constraint);
    
    /**
     * Adds this constraint to the constraint graph
     */
    override public function addToGraph() {
      this.myOutput.addConstraint(this);
      this.satisfied = false;
    }
    
    /**
     * Decides if this constraint can be satisfied and records that
     * decision.
     */
    override public function chooseMethod(mark) {
      this.satisfied = (this.myOutput.mark != mark)
        && Strength.stronger(this.strength, this.myOutput.walkStrength);
    }
    
    /**
     * Returns true if this constraint is satisfied in the current solution.
     */
    override public function isSatisfied() {
      return this.satisfied;
    }
    
    override public function markInputs(mark) {
      // has no inputs
    }
    
    /**
     * Returns the current output variable.
     */
    override public function output() {
      return this.myOutput;
    }
    
    /**
     * Calculate the walkabout strength, the stay flag, and, if it is
     * 'stay', the value for the current output of this constraint. Assume
     * this constraint is satisfied.
     */
    override public function recalculate() {
      this.myOutput.walkStrength = this.strength;
      this.myOutput.stay = !this.isInput();
      if (this.myOutput.stay) this.execute(); // Stay optimization
    }
    
    /**
     * Records that this constraint is unsatisfied
     */
    override public function markUnsatisfied() {
      this.satisfied = false;
    }
    
    override public function inputsKnown(mark=null) {
      return true;
    }
    
    override public function removeFromGraph() {
      if (this.myOutput != null) this.myOutput.removeConstraint(this);
      this.satisfied = false;
    }
} // class UnaryConstraint

/* --- *
 * S t a y   C o n s t r a i n t
 * --- */
public class StayConstraint extends UnaryConstraint {
    /**
     * Variables that should, with some level of preference, stay the same.
     * Planners may exploit the fact that instances, if satisfied, will not
     * change their output during plan execution.  This is called "stay
     * optimization".
     */
    public function StayConstraint(v, str) {
      super(v, str);
    }
    
    //StayConstraint.inherits(UnaryConstraint);
    
} // class StayConstraint

/* --- *
 * E d i t   C o n s t r a i n t
 * --- */
public class EditConstraint extends UnaryConstraint {
    /**
     * A unary input constraint used to mark a variable that the client
     * wishes to change.
     */
    public function EditConstraint(v, str) {
      super(v, str);
    }
    
    //EditConstraint.inherits(UnaryConstraint);
    
    /**
     * Edits indicate that a variable is to be changed by imperative code.
     */
    override public function isInput() {
      return true;
    }
} // class EditConstraint


public class Direction {
    static public const NONE:int     = 0;
    static public const FORWARD:int  = 1;
    static public const BACKWARD:int = -1;
    
} // class Direction

/* --- *
 * B i n a r y   C o n s t r a i n t
 * --- */
public class BinaryConstraint extends Constraint {
    
    /**
     * Abstract superclass for constraints having two possible output
     * variables.
     */
    protected var v1;
    protected var v2;
    protected var direction;
    
    public function BinaryConstraint(var1, var2, strength) {
      super(strength);
      this.v1 = var1;
      this.v2 = var2;
      this.direction = Direction.NONE;
      this.addConstraint();
    }
    
    //BinaryConstraint.inherits(Constraint);
    
    /**
     * Decides if this constratint can be satisfied and which way it
     * should flow based on the relative strength of the variables related,
     * and record that decision.
     */
    override public function chooseMethod(mark) {
      if (this.v1.mark == mark) {
        this.direction = (this.v1.mark != mark && Strength.stronger(this.strength, this.v2.walkStrength))
          ? Direction.FORWARD
          : Direction.NONE;
      }
      if (this.v2.mark == mark) {
        this.direction = (this.v1.mark != mark && Strength.stronger(this.strength, this.v1.walkStrength))
          ? Direction.BACKWARD
          : Direction.NONE;
      }
      if (Strength.weaker(this.v1.walkStrength, this.v2.walkStrength)) {
        this.direction = Strength.stronger(this.strength, this.v1.walkStrength)
          ? Direction.BACKWARD
          : Direction.NONE;
      } else {
        this.direction = Strength.stronger(this.strength, this.v2.walkStrength)
          ? Direction.FORWARD
          : Direction.BACKWARD
      }
    }
    
    /**
     * Add this constraint to the constraint graph
     */
    override public function addToGraph() {
      this.v1.addConstraint(this);
      this.v2.addConstraint(this);
      this.direction = Direction.NONE;
    }
    
    /**
     * Answer true if this constraint is satisfied in the current solution.
     */
    override public function isSatisfied() {
      return this.direction != Direction.NONE;
    }
    
    /**
     * Mark the input variable with the given mark.
     */
    override public function markInputs(mark) {
      this.input().mark = mark;
    }
    
    /**
     * Returns the current input variable
     */
    public function input() {
      return (this.direction == Direction.FORWARD) ? this.v1 : this.v2;
    }
    
    /**
     * Returns the current output variable
     */
    override public function output() {
      return (this.direction == Direction.FORWARD) ? this.v2 : this.v1;
    }
    
    /**
     * Calculate the walkabout strength, the stay flag, and, if it is
     * 'stay', the value for the current output of this
     * constraint. Assume this constraint is satisfied.
     */
    override public function recalculate() {
      var ihn = this.input(), out = this.output();
      out.walkStrength = Strength.weakestOf(this.strength, ihn.walkStrength);
      out.stay = ihn.stay;
      if (out.stay) this.execute();
    }
    
    /**
     * Record the fact that this constraint is unsatisfied.
     */
    override public function markUnsatisfied() {
      this.direction = Direction.NONE;
    }
    
    override public function inputsKnown(mark=null) {
      var i = this.input();
      return i.mark == mark || i.stay || i.determinedBy == null;
    }
    
    override public function removeFromGraph() {
      if (this.v1 != null) this.v1.removeConstraint(this);
      if (this.v2 != null) this.v2.removeConstraint(this);
      this.direction = Direction.NONE;
    }
} // class BinaryConstraint


/* --- *
 * S c a l e   C o n s t r a i n t
 * --- */
public class ScaleConstraint extends BinaryConstraint {
    /**
     * Relates two variables by the linear scaling relationship: "v2 =
     * (v1 * scale) + offset". Either v1 or v2 may be changed to maintain
     * this relationship but the scale factor and offset are considered
     * read-only.
     */
    protected var scale;
    protected var offset;
    
    public function ScaleConstraint(src, scale, offset, dest, strength) {
      this.direction = Direction.NONE;
      this.scale = scale;
      this.offset = offset;
      super(src, dest, strength);
    }
    
    //ScaleConstraint.inherits(BinaryConstraint);
    
    /**
     * Adds this constraint to the constraint graph.
     */
    override public function addToGraph() {
        super.addToGraph();
        this.scale.addConstraint(this);
        this.offset.addConstraint(this);
    }
    
    override public function removeFromGraph() {
      super.removeFromGraph();
      if (this.scale != null) this.scale.removeConstraint(this);
      if (this.offset != null) this.offset.removeConstraint(this);
    }
    
    override public function markInputs(mark) {
      super.markInputs(mark);
      this.scale.mark = this.offset.mark = mark;
    }
    
    /**
     * Enforce this constraint. Assume that it is satisfied.
     */
    override public function execute() {
      if (this.direction == Direction.FORWARD) {
        this.v2.value = this.v1.value * this.scale.value + this.offset.value;
      } else {
        this.v1.value = (this.v2.value - this.offset.value) / this.scale.value;
      }
    }
    
    /**
     * Calculate the walkabout strength, the stay flag, and, if it is
     * 'stay', the value for the current output of this constraint. Assume
     * this constraint is satisfied.
     */
    override public function recalculate() {
      var ihn = this.input(), out = this.output();
      out.walkStrength = Strength.weakestOf(this.strength, ihn.walkStrength);
      out.stay = ihn.stay && this.scale.stay && this.offset.stay;
      if (out.stay) this.execute();
    }
} // class ScaleConstraint

/* --- *
 * E q u a l i t  y   C o n s t r a i n t
 * --- */
public class EqualityConstraint extends BinaryConstraint {
    /**
     * Constrains two variables to have the same value.
     */
    public function EqualityConstraint(var1, var2, strength) {
      super(var1, var2, strength);
    }
    
    //EqualityConstraint.inherits(BinaryConstraint);
    
    /**
     * Enforce this constraint. Assume that it is satisfied.
     */
    override public function execute() {
      this.output().value = this.input().value;
    }
} // class EqualityConstraint

/* --- *
 * V a r i a b l e
 * --- */
public class Variable {
    /**
     * A constrained variable. In addition to its value, it maintain the
     * structure of the constraint graph, the current dataflow graph, and
     * various parameters of interest to the DeltaBlue incremental
     * constraint solver.
     **/
    public var value;
    public var constraints;
    public var determinedBy;
    public var mark;
    public var walkStrength;
    public var stay;
    public var name;
    
    function Variable(name, initialValue = 0) {
      this.value = initialValue;
      this.constraints = new OrderedCollection();
      this.determinedBy = null;
      this.mark = 0;
      this.walkStrength = Strength.WEAKEST;
      this.stay = true;
      this.name = name;
    }
    
    /**
     * Add the given constraint to the set of all constraints that refer
     * this variable.
     */
    public function addConstraint(c) {
      this.constraints.add(c);
    }
    
    /**
     * Removes all traces of c from this variable.
     */
    public function removeConstraint(c) {
      this.constraints.remove(c);
      if (this.determinedBy == c) this.determinedBy = null;
    }
} // class Variable

/* --- *
 * P l a n n e r
 * --- */
public class Planner {
    /**
     * The DeltaBlue planner
     */
    public var currentMark;
    
    public function Planner() {
      this.currentMark = 0;
    }
    
    /**
     * Attempt to satisfy the given constraint and, if successful,
     * incrementally update the dataflow graph.  Details: If satifying
     * the constraint is successful, it may override a weaker constraint
     * on its output. The algorithm attempts to resatisfy that
     * constraint using some other method. This process is repeated
     * until either a) it reaches a variable that was not previously
     * determined by any constraint or b) it reaches a constraint that
     * is too weak to be satisfied using any of its methods. The
     * variables of constraints that have been processed are marked with
     * a unique mark value so that we know where we've been. This allows
     * the algorithm to avoid getting into an infinite loop even if the
     * constraint graph has an inadvertent cycle.
     */
    public function incrementalAdd(c) {
      var mark = this.newMark();
      var overridden = c.satisfy(mark);
      while (overridden != null)
        overridden = overridden.satisfy(mark);
    }
    
    /**
     * Entry point for retracting a constraint. Remove the given
     * constraint and incrementally update the dataflow graph.
     * Details: Retracting the given constraint may allow some currently
     * unsatisfiable downstream constraint to be satisfied. We therefore collect
     * a list of unsatisfied downstream constraints and attempt to
     * satisfy each one in turn. This list is traversed by constraint
     * strength, strongest first, as a heuristic for avoiding
     * unnecessarily adding and then overriding weak constraints.
     * Assume: c is satisfied.
     */
    public function incrementalRemove(c) {
      var out = c.output();
      c.markUnsatisfied();
      c.removeFromGraph();
      var unsatisfied = this.removePropagateFrom(out);
      var strength = Strength.REQUIRED;
      do {
        for (var i = 0; i < unsatisfied.size(); i++) {
          var u = unsatisfied.at(i);
          if (u.strength == strength)
            this.incrementalAdd(u);
        }
        strength = strength.nextWeaker();
      } while (strength != Strength.WEAKEST);
    }
    
    /**
     * Select a previously unused mark value.
     */
    public function newMark() {
      return ++this.currentMark;
    }
    
    /**
     * Extract a plan for resatisfaction starting from the given source
     * constraints, usually a set of input constraints. This method
     * assumes that stay optimization is desired; the plan will contain
     * only constraints whose output variables are not stay. Constraints
     * that do no computation, such as stay and edit constraints, are
     * not included in the plan.
     * Details: The outputs of a constraint are marked when it is added
     * to the plan under construction. A constraint may be appended to
     * the plan when all its input variables are known. A variable is
     * known if either a) the variable is marked (indicating that has
     * been computed by a constraint appearing earlier in the plan), b)
     * the variable is 'stay' (i.e. it is a constant at plan execution
     * time), or c) the variable is not determined by any
     * constraint. The last provision is for past states of history
     * variables, which are not stay but which are also not computed by
     * any constraint.
     * Assume: sources are all satisfied.
     */
    public function makePlan(sources) {
      var mark = this.newMark();
      var plan = new Plan();
      var todo = sources;
      while (todo.size() > 0) {
        var c = todo.removeFirst();
        if (c.output().mark != mark && c.inputsKnown(mark)) {
          plan.addConstraint(c);
          c.output().mark = mark;
          this.addConstraintsConsumingTo(c.output(), todo);
        }
      }
      return plan;
    }
    
    /**
     * Extract a plan for resatisfying starting from the output of the
     * given constraints, usually a set of input constraints.
     */
    public function extractPlanFromConstraints(constraints) {
      var sources = new OrderedCollection();
      for (var i = 0; i < constraints.size(); i++) {
        var c = constraints.at(i);
        if (c.isInput() && c.isSatisfied())
          // not in plan already and eligible for inclusion
          sources.add(c);
      }
      return this.makePlan(sources);
    }
    
    /**
     * Recompute the walkabout strengths and stay flags of all variables
     * downstream of the given constraint and recompute the actual
     * values of all variables whose stay flag is true. If a cycle is
     * detected, remove the given constraint and answer
     * false. Otherwise, answer true.
     * Details: Cycles are detected when a marked variable is
     * encountered downstream of the given constraint. The sender is
     * assumed to have marked the inputs of the given constraint with
     * the given mark. Thus, encountering a marked node downstream of
     * the output constraint means that there is a path from the
     * constraint's output to one of its inputs.
     */
    public function addPropagate(c, mark) {
      var todo = new OrderedCollection();
      todo.add(c);
      while (todo.size() > 0) {
        var d = todo.removeFirst();
        if (d.output().mark == mark) {
          this.incrementalRemove(c);
          return false;
        }
        d.recalculate();
        this.addConstraintsConsumingTo(d.output(), todo);
      }
      return true;
    }
    
    
    /**
     * Update the walkabout strengths and stay flags of all variables
     * downstream of the given constraint. Answer a collection of
     * unsatisfied constraints sorted in order of decreasing strength.
     */
    public function removePropagateFrom(out) {
      out.determinedBy = null;
      out.walkStrength = Strength.WEAKEST;
      out.stay = true;
      var unsatisfied = new OrderedCollection();
      var todo = new OrderedCollection();
      todo.add(out);
      while (todo.size() > 0) {
        var v = todo.removeFirst();
        for (var i = 0; i < v.constraints.size(); i++) {
          var c = v.constraints.at(i);
          if (!c.isSatisfied())
            unsatisfied.add(c);
        }
        var determining = v.determinedBy;
        for (var i = 0; i < v.constraints.size(); i++) {
          var next = v.constraints.at(i);
          if (next != determining && next.isSatisfied()) {
            next.recalculate();
            todo.add(next.output());
          }
        }
      }
      return unsatisfied;
    }
    
    public function addConstraintsConsumingTo(v, coll) {
      var determining = v.determinedBy;
      var cc = v.constraints;
      for (var i = 0; i < cc.size(); i++) {
        var c = cc.at(i);
        if (c != determining && c.isSatisfied())
          coll.add(c);
      }
    }

} // class Planner

/* --- *
 * P l a n
 * --- */

public class Plan {
    /**
     * A Plan is an ordered list of constraints to be executed in sequence
     * to resatisfy all currently satisfiable constraints in the face of
     * one or more changing inputs.
     */
    public var v;
    
    public function Plan() {
      this.v = new OrderedCollection();
    }
    
    public function addConstraint(c) {
      this.v.add(c);
    }
    
    public function size() {
      return this.v.size();
    }
    
    public function constraintAt(index) {
      return this.v.at(index);
    }
    
    public function execute() {
      for (var i = 0; i < this.size(); i++) {
        var c = this.constraintAt(i);
        c.execute();
      }
    }

} // class Plan

/* --- *
 * M a i n
 * --- */

/**
 * This is the standard DeltaBlue benchmark. A long chain of equality
 * constraints is constructed with a stay constraint on one end. An
 * edit constraint is then added to the opposite end and the time is
 * measured for adding and removing this constraint, and extracting
 * and executing a constraint satisfaction plan. There are two cases.
 * In case 1, the added constraint is stronger than the stay
 * constraint and values must propagate down the entire length of the
 * chain. In case 2, the added constraint is weaker than the stay
 * constraint so it cannot be accomodated. The cost in this case is,
 * of course, very low. Typical situations lie somewhere between these
 * two extremes.
 */
 
function chainTest(n) {
  planner = new Planner();
  var prev = null, first = null, last = null;

  // Build chain of n equality constraints
  for (var i = 0; i <= n; i++) {
    var name = "v" + i;
    var v = new Variable(name);
    if (prev != null)
      new EqualityConstraint(prev, v, Strength.REQUIRED);
    if (i == 0) first = v;
    if (i == n) last = v;
    prev = v;
  }

  new StayConstraint(last, Strength.STRONG_DEFAULT);
  var edit = new EditConstraint(first, Strength.PREFERRED);
  var edits = new OrderedCollection();
  edits.add(edit);
  var plan = planner.extractPlanFromConstraints(edits);
  for (var i = 0; i < 100; i++) {
    first.value = i;
    plan.execute();
    if (last.value != i)
      print("Chain test failed.");
  }
}

/**
 * This test constructs a two sets of variables related to each
 * other by a simple linear transformation (scale and offset). The
 * time is measured to change a variable on either side of the
 * mapping and to change the scale and offset factors.
 */
function projectionTest(n) {
  planner = new Planner();
  var scale = new Variable("scale", 10);
  var offset = new Variable("offset", 1000);
  var src = null, dst = null;

  var dests = new OrderedCollection();
  for (var i = 0; i < n; i++) {
    src = new Variable("src" + i, i);
    dst = new Variable("dst" + i, i);
    dests.add(dst);
    new StayConstraint(src, Strength.NORMAL);
    new ScaleConstraint(src, scale, offset, dst, Strength.REQUIRED);
  }

  change(src, 17);
  if (dst.value != 1170) print("Projection 1 failed");
  change(dst, 1050);
  if (src.value != 5) print("Projection 2 failed");
  change(scale, 5);
  for (var i = 0; i < n - 1; i++) {
    if (dests.at(i).value != i * 5 + 1000)
      print("Projection 3 failed");
  }
  change(offset, 2000);
  for (var i = 0; i < n - 1; i++) {
    if (dests.at(i).value != i * 5 + 2000)
      print("Projection 4 failed");
  }

  print(dests.at(30).value);
}

function change(v, newValue) {
  var edit = new EditConstraint(v, Strength.PREFERRED);
  var edits = new OrderedCollection();
  edits.add(edit);
  var plan = planner.extractPlanFromConstraints(edits);
  for (var i = 0; i < 10; i++) {
    v.value = newValue;
    plan.execute();
  }
  edit.destroyConstraint();
}

// Global variable holding the current planner.
var planner = null;

function deltaBlue() {
  chainTest(100);
  projectionTest(100);
}

deltaBlue();
} // package
